A method of manufacture for an acoustic resonator or filter device. In an example, the present method can include forming metal electrodes with different geometric areas and profile shapes coupled to a piezoelectric layer overlying a substrate. These metal electrodes can also be formed within cavities of the piezoelectric layer or the substrate with varying geometric areas. Combined with specific dimensional ratios and ion implantations, such techniques can increase device performance metrics. In an example, the present method can include forming various types of perimeter structures surrounding the metal electrodes, which can be on top or bottom of the piezoelectric layer. These perimeter structures can use various combinations of modifications to shape, material, and continuity. These perimeter structures can also be combined with sandbar structures, piezoelectric layer cavities, the geometric variations previously discussed to improve device performance metrics.

Disclosed herein are embodiments of a method of manufacturing film bulk acoustic wave resonators. The method comprises forming a sacrificial layer over a surface of a substrate to form a plurality of film bulk acoustic wave resonators on the surface of the substrate, forming a piezoelectric film on the surface of the substrate to cover the sacrificial layer, and removing the sacrificial layer to form an air gap between the surface of the substrate and the piezoelectric film that has covered the sacrificial layer, the air gap corresponding to each of the plurality of film bulk acoustic wave resonators. The step of forming the piezoelectric film includes controlling a concentration distribution of an additive added to the piezoelectric film across the surface of the substrate to suppress a variation of the acoustic velocity of the piezoelectric film depending on a position on the main surface of the substrate.

An acoustic wave filter provided herein comprises a plurality of series resonators, and a plurality of shunt resonators disposed between the series resonators and a ground, at least one shunt resonator including a substrate, a pair of IDT electrodes disposed on the substrate, each of the IDT electrodes including a bus bar and a plurality of fingers extending from the bus bar, the plurality of fingers of the pair of IDT electrodes including a first group of fingers located at a center region of the pair of IDT electrodes and a second group of fingers located at edge regions on both sides of the center region, the first group of fingers having an average pitch distance shorter than an average pitch distance of the second group of fingers to improve a response at a rejection band of the acoustic wave filter.

A filter may include a substrate and a rotated YX-cut piezoelectric plate coupled to the substrate. The filter also may include an interdigital transducer (IDT) formed on a portion of the rotated YX-cut piezoelectric plate forming a diaphragm that spans a cavity between the rotated YX-cut piezoelectric plate and the substrate. The IDT includes interleaved fingers that are disposed on the diaphragm. The IDT has an aperture that is less than or equal to 4 times a pitch of the interleaved fingers.

A method of manufacture for an acoustic resonator or filter device. In an example, the present method can include forming metal electrodes with different geometric areas and profile shapes coupled to a piezoelectric layer overlying a substrate. These metal electrodes can also be formed within cavities of the piezoelectric layer or the substrate with varying geometric areas. Combined with specific dimensional ratios and ion implantations, such techniques can increase device performance metrics. In an example, the present method can include forming various types of perimeter structures surrounding the metal electrodes, which can be on top or bottom of the piezoelectric layer. These perimeter structures can use various combinations of modifications to shape, material, and continuity. These perimeter structures can also be combined with sandbar structures, piezoelectric layer cavities, the geometric variations previously discussed to improve device performance metrics.

An acoustic wave filter device is disclosed. The device includes an acoustic wave filter element, and a first resonator and a second resonator coupled to the acoustic wave filter element. The acoustic wave filter element includes interdigited input electrodes and output electrodes located on a top surface of a piezoelectric layer. Each of the first and the second resonators includes a top electrode on the top surface, and a bottom electrode on the bottom surface of the piezoelectric layer. At least one of each of the first and the second resonators' electrodes is electrically connected to the acoustic wave filter element. The first resonator has a first notch in resonator impedance at a first frequency. The second resonator includes a first mass loading layer on the second resonator electrode such that the second resonator has a second notch in resonator impedance at a second frequency different from the first frequency.

An acoustic wave device includes a support substrate, a piezoelectric layer, an energy confining layer, a first resonator, and a second resonator. The piezoelectric layer includes a first principal surface and includes lithium niobate or lithium tantalate. The energy confining layer is provided between the support substrate and the piezoelectric layer. Each of the first resonator and the second resonator includes at least one pair of a first electrode and a second electrode provided to the first principal surface of the piezoelectric layer. The first resonator is structured to generate a thickness-shear mode bulk wave, and the second resonator is structured to generate a wave other than a thickness-shear mode bulk wave.

A filter device includes a filter substrate and a ladder filter at the filter substrate. The ladder filter includes at least one inductor and acoustic wave resonators including a series arm resonator and a parallel arm resonator. The at least one inductor is coupled to the acoustic wave resonators. A pass bandwidth of the ladder filter is larger than a resonance bandwidth of at least one of the acoustic wave resonators. The series arm resonator includes a first piezoelectric substrate. The parallel arm resonator includes a second piezoelectric substrate that is different from the first piezoelectric substrate.

A method of manufacture for an acoustic resonator or filter device. In an example, the present method can include forming metal electrodes with different geometric areas and profile shapes coupled to a piezoelectric layer overlying a substrate. These metal electrodes can also be formed within cavities of the piezoelectric layer or the substrate with varying geometric areas. Combined with specific dimensional ratios and ion implantations, such techniques can increase device performance metrics. In an example, the present method can include forming various types of perimeter structures surrounding the metal electrodes, which can be on top or bottom of the piezoelectric layer. These perimeter structures can use various combinations of modifications to shape, material, and continuity. These perimeter structures can also be combined with sandbar structures, piezoelectric layer cavities, the geometric variations previously discussed to improve device performance metrics.

A composite filter device includes a ladder filter and at least one bandpass filter including one end connected in common to the ladder filter, the ladder filter including at least one serial arm resonator including a first serial arm resonator and at least one parallel arm resonator including a first parallel arm resonator. The first serial arm resonator is the closest serial arm resonator to a common terminal, and the first parallel arm resonator is the closest parallel arm resonator to the common terminal. Expression (1), Expression (2), or Expression (3) is satisfied, where a duty of an IDT of the first serial arm resonator is Sa, a duty of an IDT of the first parallel arm resonator is Pa, and a duty of an IDT of each of serial arm resonators other than the first serial arm resonator and of parallel arm resonators other than the first parallel arm resonator is Ta:

Sa<Pa<Ta   Expression (1)

Ta<Sa<Pa   Expression (2)

Pa<Ta<Sa   Expression (3).